How it works,all the way down.
Nothing here asks for your trust. Every claim on this page is a property of the construction - encryption that happens on your device, keys that are sealed to named wallets, and a network that stores what it cannot read.
One ITZA account, and it is the key.
You sign in with the same username and password as every ITZA app. On your own device, those credentials are stretched into cryptographic keys - the network registers only the resulting public identity. The password itself never leaves your browser, and no copy of it exists anywhere.
That is also why there is no reset and no recovery email. A diary that support staff could recover for you is a diary support staff could open. Pick a strong password, and one you will remember - it is the whole lock.
A fresh key for every entry.
When you save an entry, your browser generates a new 256-bit AES key for that entry alone. The title, the text and every attachment are encrypted under it. Then the key itself is sealed - asymmetrically encrypted - to your wallet, and to the wallet of each person you have given access.
What reaches the network is ciphertext and sealed keys, nothing else. Because each entry has its own key, taking someone’s access away has teeth: entries written after the removal simply carry no key for them, and no amount of password knowledge opens what was never addressed to you.
Write
Plain text and attachments, on your device, encrypted drafts only.
Seal
A fresh key encrypts the entry; the key is sealed per reader.
Store
The network keeps the ciphertext and the sealed keys - noise to everyone else.
Read
You, or a guest, unseal the key locally and decrypt on the device that reads.
Guests without accounts.
You choose a name and a password for each of up to three guests, and hand them over however you like - across a kitchen table, over the phone, in a sealed envelope. They open your diary link, type the pair, and read. No account, no signup, no app.
Those credentials are scoped to your diary alone: they derive a keypair that exists for nothing else, cannot be an ITZA account, and cannot collide with one. A wrong password does not hit a login server - it simply fails to decrypt, which is the whole failure mode. Nothing to lock out, nothing to reset, no oracle for an attacker to question.
Why it survives your phone.
Entries are stored as assets on the ITZA Blockchain, replicated by independent nodes. Storage is paid by a tiny rent in the network’s coin; a small starting allocation is granted to every new account and covers a long run of writing. Every figure the app shows you comes from the chain itself, and every fetched byte is verified before your browser trusts it.
The upshot is a diary with no single machine to lose: sign in anywhere and it is there, and no operator of any one node can read, alter or quietly delete it.
The AI reading, precisely.
Importing a paper diary photographs its pages. If you want a page transcribed by AI, that page - and only that page - is sealed for the platform’s reading worker and sent through the network. The worker decrypts it, has Anthropic’s Claude transcribe it, seals the words back to your wallet, and posts them. The price is stated per page before you send, charged from your balance, and every charge appears in your billing pane from the contract’s own record.
A page you never send is never seen by anyone, AI included. The consent card in the app says exactly this, every time, because sending a page of your diary anywhere should never happen by default.
Said plainly.
Client-side encryption hides content, not existence. The network can see that an account keeps a diary, how many entries it holds, roughly how large they are and when they were written. Guest labels you write for yourself are sealed; the diary is private, not anonymous.
Removing a guest cannot un-read the past: entries written while they had access still carry a key sealed to them. And erasing your account removes every entry, key and record from the contract - but transactions already written to a public ledger cannot be unwritten. Nothing in them was ever readable without your keys, and after erasure the keys are gone for good.